The temperature control systems provided in vehicles are generally configured to heat the air to be introduced into the interior of a vehicle by heat generated in the combustion operation of an internal combustion engine being transferred to the air to be introduced into the vehicle interior in a heat exchanger. The air to be introduced into the vehicle interior may, if necessary, also be cooled by a vehicle air-conditioning system.
If system areas are subsequently integrated as retrofit systems into such a vehicle temperature control system, their actuation-related linking with system areas that are already present in the vehicle is difficult to implement. The system areas and control units which are already present in a vehicle generally communicate via a vehicle data bus, for example, via a CAN bus, to which retrofit systems generally cannot be connected. As a result, such retrofit systems, for example, a vehicle heater to be retrofitted as a parking heater, can only be operated with limited functionality, and especially cannot act on system areas of the vehicle temperature control system that are already present in a vehicle.